Producing aromatic amins and catalysts therefor.



OTTO SCHMIDT, F LUDWIGSHAFEN-ON-THE-RHINE, GERMANY, A SSIGNOR T0 IBAJDISCHE ANILIN & SODA FAIBBIK, OF LUDWIGSHAFIEN-ON-THE-RHINE,

ennrr PRODUCING AROMATIC AMINS AND CATALYSTS THEREFOR.

raoaeoa No Drawing.

To all whom it may concern Beit knoavn that T, Orro SCHMIDT, a citizen of the German Empire, residing at Ludwigshafen-on-the-Rhine, Germany, have invented new and useful Improvements in Producing Aromatic Amins and Catalysts Therefor, of which the following is a specification.

The specification ofGerman Patent. No. 139,457 describes the production of anilin and homologues thereof by passing the corresponding nitro compounds, in the form of vapor, together with hydrogen over heated copper, nickel, cobalt, iron, or platinum and of these copper is particularly recommended, it bein stated that it may be used in the form o fine shavings, or of copper dust, or as obtained by the reduction of black copper oxid and at a temperature of from 300 to 400 C. and, according to the said specification a temperature of from 300 to 400 C. should be employed during the reduction of the aromatic nitro compounds. I have found that when such temperatures are employed, decomposition takes place, and that it is not possible, according to the said proc-" ess, to carry out the reaction continuously for the production of a good yield of pure aromatic amins. The said process has not come into commercial use and the patent was allowed to lapse.

I have found that catalytic agents containing copper prepared pyrogenetically from a salt thereof and a body promoting the action of the said copper are considerably more active for the purpose of manufacturing aromatic amins. T prefer to employ a low temperature while producing thev copper pyrogenetically from a salt thereof and, if necessary, T can employ a reducing gas such, for instance, ascarbon monoxid, or hydrogen. As suitable copper salts, I mention copper carbonate, copper formate, copper oxalate, and copper nitrate, or' mixtures of such salts with ammonium carbonate, or similar salts, may be used. When employing copper formate for the said preparation it is not necessary to employ a reducing gas. During the production of the catalytic agent it is preferred to avoid temperatures above 300 Qand in many cases an intermediate formation of copper oxid takes place. The copper obtained, in ad- Specification of Letters Patent. r g-m m y 19, 12, 1 mm Application filed 0ctober 21, 1914. Serial No. 867,715. 7

mixture with the body promoting its action, can either be employed as such, or the mixture can be placed on carriers, for instance,

Patent No. 2306 A. D. 1914. Other suitable bodies which promote the activity of the pyrogenetic copper include other heavy metals or compounds thereof, for instance, an oxid, or salt, of iron, silver, zinc or the like. The addition of the body which will promote the reaction may be made to the copper salt before the pyrogenetic conversion thereof, or such bodies may be added to the copper oxid intermediately obtained, or even to the finely divided copper itself.

According to the present invention it is possible to efiect the reduction ofaromatic nitro compounds at comparatively low temperatures, for instance at 200 (1., or less,

and a good yield of pure amin can be ob tained and the process be carried on continuv ously. It is preferred to avoid high'temperatures during the reduction as they tend to give rise both to less pure products and to lessen the activity of the contact masses.

In order to efiect the reduction of the nitro compound, it may be passed over a catalytic mixture as hereinbefore described together with hydrogen, under which term I include gas mixtures containing hydrogen, and-ll have found that water-gas, or other gas mixture containing carbon monoxid and hydrogen, is also useful for the purposes of this invention and that the carbon monoxid assists in the reduction notmay be used in carrying out the process.

The following examples will serve to illustrate further the nature of this invention, which, however, is not confined to these examples. The parts are by weight.

Example 1: Mix together, to a paste, 130 parts of pumice, 25 parts of copper oxalate, 1 part of magnesium oxid and a little water. Then dry the mass in an oven and heat it to about 200 C. and pass a current of hydrogen over it. Then, at a temperature of from contact mass,

200, to 220, (1, pass a mixture of orthonitro-toluene vapor and hydrogen over the and cool the resulting gases. A mixtureof ortho-toluidin and Water is. obtained. The ortho-toluidin can be separated in the usual, or any suitable, manner.

Example 2: Prepare a paste from 130 parts of pumice and a mixture of 20 parts of a 40 per cent. sodium silicate solution, 24.3 parts of copper carbonate,'2.7 parts of zinc carbonate and a little water.

pass over the catalytic agent a mixture of nitrobenzene vapor with excess of hydrogen while maintaining an internal temperature 1 of about 200 C. Cool the gases asthey leave the furnace. A mixture of anilin and Water is obtained, fromwhich the anilin can be separated and obtained practically pure and in quantitative yield, while the catalytic agent retains its activity for a long period.

per produced pyrogenetically from its salts can be employed.

pumice, 24 parts of Example 4: Mi; together 130 parts of a mixture containing 90 per cent. of coppercarbonate and 10 per cent. of zinc carbonate and 20 parts of a 40- fpI cent. solution of Water-glass, while employipg a little Water; then dry. the mass a while employing a temperature of from and reduce itin a furnace, at about 200 (1.. by means of purified water-gas, and then 190 to220 C. pass through the furnace a current containing nitrobenzene vapor and purified water-gas- On cooling the gases which leave the furnace, a mixture of anilin Introduce the mass into a furnace and reduceitgwithj hydrogen, at from 180 to 200 C. and then and Water is obtained from which the anilin can be separated in any suitable Way.

Now what I claim is l.- The process of producing an aromatic amin by passing the vapors of the corresponding nitro compound together with hydrogen over a catalytic agent containing copper prepared pyrogenetically from a salt thereof and a body promoting the action of the said copper.

2. The process of producing an aromatic amin by passing the "apors of the corresponding nitro compound together with hydrogen and carbon monoxid over a catalytic agent containing copper prepared pyrogenetically from a salt thereof and a body promoting the action of the said copper.

3. The process of producing an aromatic amin by passing the vapors of the corresponding nitro compound together with hydrogen over a catalytic agent containing copper prepared pyrogenetically from a salt thereof and-a body containing zinc.

4. The process of producing an aromatic amin by passing the vapors of the corresponding nitro compound .together with hydrogen and carbon 'monoxid over a catalytic agent containing copper prepared pyrogenetically from a salt thereof and a body containing zinc.

. 5. The process of producing anilin by passing vaporized nitrobenzene together with hydrogen over a catalytic agent containing copper prepared pyrogenetically from a salt thereof and a .body promoting the action of the said copper.

6. The process of producing anilin by passing vaporized nitrobenzene together with hydrogen and carbon monoxid over a catalytic agent containing copper prepared pyrogenetically from a salt thereof, and a body containing zinc.

In testimony whereof I have hereunto set my hand in the presence of two subscribing Witnesses.

- r OTTO SCHMIDT. Witnesses:

MARX BUCH, Jr.,

RUPERT LA'UFER. 

